This invention relates to a process and apparatus for regulating an interior temperature of a motor vehicle.
A process and apparatus for controlling an interior space temperature, particularly for a motor vehicle, of a type of this invention is disclosed in European Patent application 0 083 048. This patent application describes a control apparatus for a heater and/or air conditioner for motor vehicles which has an electrical controller coupled via a first subtractor to a nominal temperature provider and an interior space temperature sensor as well as to an output stage for directionally driving a motor. The motor thereby adjusts the position of an adjustable member which influences the amount of heat channeled to an interior space. In this system, a nominal temperature is set, or fixed, and an interior space temperature is sensed or measured. The first subtractor forms from the nominal temperature and the interior space temperature a first difference value which is fed to the controller. The controller forms from this first difference value a controlling value which it feeds to the output stage and, depending upon the control value, cyclically, or reoccurringly, drives the motor. The motor adjusts the adjustable member to influence the amount of heat fed to the interior space in dependence upon the set nominal temperature and the sensed interior space temperature. Additionally, a position signal of the adjustable member is measured and fed into a control loop in the form of a positioning control loop. The positioning control loop is often, for example as is disclosed in German Offenlegungsschrift DE-OS 35 10 648, of a type in which a potentiometer that is coupled to the adjustable member delivers a voltage value, which depends upon the position of the adjustable member, to the controller or to the control loop in order that the position of the adjustable member is taken into consideration upon controlling the interior space temperature.
A disadvantage of this system is that control of interior space temperature for two different separated space zones is achieved so that a large expense for construction parts is necessary which leads directly to higher costs and which also causes production and mounting thereof to be more expensive.
A particular disadvantage of this prior-art control apparatus and process is that by using a potentiometer to form a position signal, an exact and reliable measurement of the position of the adjustable member is not possible because a potentiometer does not have a necessary precision for measuring and forming a position signal, and circuits for correcting errors arising during measurements with potentiometers are expensive.
In this regard, a particularly disadvantage of producing and mounting an apparatus for controlling interior space temperature, using a potentiometer to establish a position signal, is that it is not cost effective because when mounting the potentiometer and the adjustable member a costly calibration is necessary, with the potentiometer needing a lot of space.
In addition, the prior art apparatus for controlling interior space temperature has proven to be disadvantageous in that it is difficult and expensive to adapt for use in controlling various types of interior spaces.
It is an object of this invention to provide a process and apparatus for controlling an interior space temperature of a motor vehicle which is uncomplicated, has small space requirements, is cost effective, and, by using a DC motor for adjusting an adjustable member, guarantees an exact and reliable positioning of the adjustable member, with the apparatus being mountable and producible in an uncomplicated and cost effective manner, without the use of a costly mount, and which can be adapted for use with various interior spaces.
According to principles of this invention, a position signal is formed by measuring and analyzing partial movements of a dc motor through a predetermined angle for each activation and further rotation of the dc motor.